1. Field of the Invention
This invention relates to an infusion syringe apparatus for applying and monitoring fluid pressure applied to the intervertebral disk of the spinal column, or more specifically, monitoring of the pressure applied through a needle or cannula through the annulus fibrosus of the disk and into the nucleus pulposus thus allowing the diagnosis of diseased or ruptured disks. The field may further include fluid pressure-inducing syringes and methods involved in percutaneous translumental angioplasty (PTA) procedures.
2. State of the Art
Infusers utilized in diskography and balloon angioplasty are well known and established in medical practice. The tools typically applied to angioplasty have found application in other fields as well, including opening diseased carotid arteries, improving or reestablishing blood flow to the extremities of diabetics, and similar procedures. Similar tools have been used in the field of pain diagnosis and management related to orthopedic procedures related to the spine.
The number of failed or ineffectual spine surgeries has driven the development of new techniques for verifying the location of damage or injury in the vertebral column. Typically, these procedures involve the insertion of a curved or specifically shaped cannula or needle under the transverse process of the vertebra and around the inferior articular process and penetrating the annulus fibrosus. Application of fluid pressure to the nucleus pulposus will either go undetected, create relief from chronic pain, or induce a pain episode due to the pinching of a nerve. By the application of this technique to suspect vertebral disks, a physician can identify the pain locus and, thus, use the appropriate intervention to provide relief for the patient. This process is typically performed utilizing ionic contrast media, typically made from ionically bound iodine. This media allows the physician to view the procedure on a fluoroscope, which aids in needle positioning and visual diagnosis. Diagnosis is based on the ability, or inability, of the end of inter-vertebral disks to contain the contrast media when it is injected under pressure into the nucleus pulposus of the disk.
Typically, any syringe with a mechanism for measuring pressure has been used to measure the patency of the inter-vertebral disk. However, such syringes typically utilize a transducer mounted at the distal end of the syringe barrel which is in communication with the fluid path of the syringe. The presence of a non-transparent transducer and associated fixtures adjacent the fluid path prevents clear vision of bubbles in the contrast media or other imperfections that may be of concern in interventional procedures. Such devices are described in U.S. Pat. Nos. 5,021,046 and 5,084,060. Also, many such devices are awkward to use, are unduly complex or fail to provide a flexible fluid pressure adjustment.